OUTCOME ASSESSMENT IN ORTHOPAEDICS USING A STAIR CLIMBING TEST AND ACCELEROMETER BASED MOTION ANALYSIS: A FEASIBILITY STUDY

Abstract

To clinically diagnose and postoperatively monitor the younger or more demanding orthopaedic patients it becomes increasingly important to measure function beyond the capacity of classic scores suffering from subjectivity, pain dominance and ceiling effects. This study investigates whether a stair climbing test with accelerometer derived motion parameters in a group of healthy subjects is clinically feasible and valid to distinguish between demographic differences.

The ascending and descending of stairs (preferred speed, no handrails) was measured in 46 healthy subjects (19m/27f, no orthopaedic pathology) using a triaxial accelerometer attached with a belt to the sacrum. The study group was divided in two age groups: young group (15m/16f; age: 25 [21–38]) and old group (4m/11f; age: 67 [54–74]). Motion parameters were derived by acceleration peak detection algorithms based on step times: tup, tdown, tup-tdown,, step irregularity: irrup, irrdown and asymmetry: asymup, asymdown.

Step times were slightly higher ascending (tup=606ms) than descending (tdown=575ms, p< 0.05). The step time difference between ascending and descending (tup-tdown=31ms) showed a significant difference between the young (47ms) and elderly (−7ms). All subjects with descending times ≥20ms slower than ascending (6/46) were elderly. Irregularity and asymmetry were similar between stepping direction and age groups. Asymmetry identified the dominant leg with equal or faster steps than the non-dominant leg in 43/46 cases. Motion parameters were not correlated to gender, height or BMI.

Slower step times down than up seem a promising parameter to detect general or bilateral orthopaedic pathologies. Asymmetry identifying the dominant leg shall detect unilateral pathologies. The accelerometer assessed stair test seems suitable for routine clinical follow-up complementing classic scores.